Solid, glyme-containing electrolytes including ion salt derivatives and electrolytic cells produced therefrom

ABSTRACT

This invention is directed to solid electrolytes containing a solvent and, in particular, a solvent comprising a mixture of an organic carbonate and an ion salt derivative (e.g., lithium) which functions as a source of ions for producing conductivity. The invention is also directed to electrolytic cells prepared from such solid electrolytes.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention is directed to solid electrolytes containing a polymermatrix and an electrolyte solvent (plasticizer) for the polymer matrix.In particular, this invention is directed to solid electrolytescontaining an ion salt derivative formed by incorporating an ion saltinto the polymer matrix and/or the solvent. The ion salt derivative canpartially or completely replace the inorganic ion salt heretofore addedto the electrolyte as a separate component in prior art electrolytecompositions.

This invention is further directed to solid electrolytic cells(batteries) containing an anode, a cathode and a solid electrolytecontaining a polymer matrix, a solvent and an ion salt derivativeincorporated into the polymer matrix and/or the solvent.

This invention is also directed to methods for enhancing the cumulativecapacity of the solid electrolytic cells by employing a solidelectrolyte which contains an ion salt derivative.

2. State of the Art

Electrolytic cells containing an anode, a cathode and a solid,solvent-containing electrolyte incorporating an inorganic ion salt areknown in the art and are usually referred to as "solid batteries". Thesecells offer a number of advantages over electrolytic cells containing aliquid electrolyte (i.e., "liquid batteries") including improved safetyfeatures. Notwithstanding their advantages, the manufacture of thesesolid batteries requires careful process control to minimize theformation of impurities due to decomposition of the inorganic ion saltwhen forming the solid electrolyte. Excessive levels of impuritiesinhibit battery performance and can significantly reduce charge anddischarge capacity.

Specifically, solid batteries employ a solid electrolyte interposedbetween a cathode and an anode. The solid electrolyte contains either aninorganic or an organic matrix and a suitable inorganic ion salt as aseparate component. The inorganic matrix may be non-polymeric [e.g,β-alumina, silver oxide, lithium iodide, etc.] or polymeric [e.g.,inorganic (polyphosphazene) polymers] whereas the organic matrix istypically polymeric. Suitable organic polymeric matrices are well knownin the art and are typically organic polymers obtained by polymerizationof a suitable organic monomer as described, for example, in U.S. Pat.No. 4,908,283. Suitable organic monomers include, by way of example,polyethylene oxide, polypropylene oxide, polyethyleneimine,polyepichlorohydrin, polyethylene succinate, and an acryloyl-derivatizedpolyalkylene oxide containing an acryloyl group of the formula CH₂═CR'C(O)O-- where R' is hydrogen or lower alkyl of from 1-6 carbonatoms.

Because of their expense and difficulty in forming into a variety ofshapes, inorganic non-polymeric matrices are generally not preferred andthe art typically employs a solid electrolyte containing a polymericmatrix. Nevertheless, electrolytic cells containing a solid electrolytecontaining a polymeric matrix suffer from low ion conductivity and,accordingly, in order to maximize the conductivity of these materials,the matrix is generally constructed into a very thin film, i.e., on theorder of about 25 to about 250 μm. As is apparent, the reduced thicknessof the film reduces the total amount of internal resistance within theelectrolyte thereby minimizing losses in conductivity due to internalresistance.

The solid electrolytes also contain a solvent (plasticizer) which, priorto the present invention, has been added to the matrix primarily inorder to enhance the solubility of the inorganic ion salt in the solidelectrolyte and thereby increase the conductivity of the electrolyticcell. In this regard, the solvent requirements of the solvent used inthe solid electrolyte have been art recognized to be different from thesolvent requirements in liquid electrolytes. For example, solidelectrolytes require a lower solvent volatility as compared to thesolvent volatilities permitted in liquid electrolytes.

Suitable solvents well known in the art for use in such solidelectrolytes include, by way of example, propylene carbonate, ethylenecarbonate, γ-butyrolactone, tetrahydrofuran, glyme (dimethoxyethane),diglyme, tetraglyme, dimethylsulfoxide, dioxolane, sulfolane and thelike.

Heretofore, the solid, solvent-containing electrolyte has typically beenformed by one of two methods. In one method, the solid matrix is firstformed and then a requisite amount of this material is dissolved in avolatile solvent. Requisite amounts of the inorganic ion salt and theelectrolyte solvent (usually a glyme and the organic carbonate) are thenadded to the solution. This solution is then placed on the surface of asuitable substrate (e.g., the surface of a cathode) and the volatilesolvent is removed to provide for the solid electrolyte.

In the other method, a monomer or partial polymer of the polymericmatrix to be formed is combined with appropriate amounts of theinorganic ion salt and the solvent. This mixture is then placed on thesurface of a suitable substrate (e.g., the surface of the cathode) andthe monomer is polymerized or cured (or the partial polymer is thenfurther polymerized or cured) by conventional techniques (heat,ultraviolet radiation, electron beams, etc.) so as to form the solid,solvent-containing electrolyte.

When the solid electrolyte is formed on a cathodic surface, an anodicmaterial can then be laminated onto the solid electrolyte to form asolid battery (i.e., an electrolytic cell).

Regardless of which of the above techniques is used in preparing thesolid electrolyte, a recurring problem has been the presence ofimpurities which interfere with cell function and can reduce batterylife. The source of these impurities is the partial decomposition of theinorganic ion salt formed in the polymer matrix. Partial decompositionoccurs due to exposure of the inorganic ion salts to the hightemperatures used, for example, in forming the polymer matrix and/or inevaporating the volatile solvent. These high temperatures cause the saltto break down into insoluble or less soluble salts. For example, lithiumhexafluorophosphate (LiPF₆) is converted to LiF, which is much lesssoluble in the electrolyte and can precipitate out. Such insoluble orless soluble salts cannot function to transfer electrons, and hence theresulting battery is rendered less efficient.

Thus, in preparing the solid electrolyte, great care must be taken tomaintain processing temperatures below the threshold level forsignificant salt decomposition. The need for careful monitoring ofprocess temperatures increases manufacturing costs and at the same timeresults in a percentage of the solid electrolyte produced being offspecification due to unavoidable process temperature variation.Electrolyte material meeting production specifications generallycontains small but tolerable levels of impurities which can neverthelessaffect cell performance, particularly with respect to cumulativecapacity. Cumulative capacity of a solid battery is defined as thesummation of the capacity of the battery over each cycle (charge anddischarge) in a specified cycle life.

Quite apart from the problem of decomposition is the cost of theinorganic ion salts. Simple salts such as lithium halides are lesspreferred in the electrolyte because they are not very compatible withthe polymers used in forming the matrix (and hence can precipitate outas mentioned above). More complex salts are favored because of theirgreater compatibility, but are more costly. A highly preferred salt isLiPF₆, but this salt has been found to be very heat sensitive and quiteexpensive. Another preferred salt is lithium hexafluoroarsenate(LiAsF₆). This salt poses significant disposal problems due to thepresence of arsenic.

Notwithstanding their complexity and costs, even under the best ofcircumstances (e.g. impurity levels approaching zero), the inorganic ionsalts typically have a transference number between 0.4 and 0.55, meaningthat the ion salt carries only between 40% and 55% of the total plus (+)charge.

In view of the above, the art is searching for methods to reduceimpurities in solid electrolyte manufacture as well as to increase thecumulative capacity of solid batteries employing such electrolytes.

SUMMARY OF THE INVENTION

The present invention is directed, in part, to the discovery that theuse of inorganic ion salt derivatives as a component of the solventand/or the polymer matrix in solid, solvent-containing electrolytesprovides for several benefits to the solid electrolyte manufacturingprocess as well as to the solid battery itself. In particular, theinvention provides for reducing or eliminating the use of inorganic ionsalts in preparing the solid electrolyte. In place of the inorganicsalts, an ion salt derivative is formed by reaction of an organometalliccompound with a hydroxyl-containing material such as an alkyleneglycol(ether) or with a monomer or partial polymer. If a monomer orpartial polymer is used, the ion salt derivative containing apolymerizable group may be subsequently incorporated into the polymermatrix of the solid electrolyte. In either case, the ion salt derivativemay be reacted further with a sultone (cyclic sulfone) to form an ionsulfonate salt.

By reducing the amount of or eliminating completely the inorganic ionsalt as a separate species within the electrolyte, a major source ofimpurities in electrolyte manufacture is removed, since the complex andheat-unstable counter ion is not present. Manufacturing costs are alsolowered since expensive, complex inorganic ion salts are no longerrequired.

Accordingly, in one of its composition aspects, this invention isdirected to a solid, single-phase, solvent-containing electrolyte whichcomprises:

a solid polymeric matrix; and

a solvent comprising about a 10:1 to 1:4 (w/w) mixture of an organiccarbonate and a glyme, and an ionically conducting amount of an ion saltderivative selected from the group consisting of:

(a) an alkylene glycol(ether) derivative represented by Formula I:

    RO(R.sub.1 O).sub.p M                                      I

or represented by Formula II:

    MO(R.sub.1 O).sub.p M                                      II

where R is selected from the group consisting of alkyl of from 1 to 6carbon atoms, phenyl, alkphenyl of from 7 to 12 carbon atoms, and phenylsubstituted with 1 to 3 substituents selected from the group consistingof alkyl of from 1 to 4 carbon atoms, alkoxy of from 1 to 4 carbonatoms, chloro and bromo;

R_(l) is (CR₃ R₄)_(q) where R₃ and R₄ are independently selected fromthe group consisting of hydrogen and alkyl of from 1 to 4 carbon atoms,q being an integer of from 1 to 6, and wherein when q is greater than 1,R₃ and R₄ on each carbon atom may be the same or different;

M is a metal ion selected from the group consisting of Li, Na, K and Mg;and

p is an integer of from 2 to 6; and

(b) an ion sulfonate salt represented by Formula III

    RO(R.sub.1 O) (CH.sub.2).sub.r SO.sub.3 M                  III

or represented by Formula IV

    MSO.sub.3 (CH.sub.2).sub.s O(R.sub.1 O) (CH.sub.2).sub.r SO.sub.3 MIV

where M, R and R₁ are as defined above and r and s are independentlyintegers from 2 to 6; and

(c) mixtures of the above.

In another of its composition aspects, the present invention is directedto an electrolytic cell which comprises:

an anode comprising a compatible anodic material;

a cathode comprising a compatible cathodic material; and

interposed therebetween a single phase, solid solvent-containingelectrolyte which comprises:

a solid polymeric matrix; and

a solvent comprising about a 10:1 to 1:4 (w/w) mixture of an organiccarbonate and a glyme, and an ionically conducting amount of an ion saltderivative selected from the group consisting of:

(a) an alkylene glycol(ether) derivative represented by Formula I:

    RO(R.sub.1 O).sub.p M                                      I

or represented by Formula II:

    MO(R.sub.1 O).sub.p M                                      II

where R and R_(l) are as described above; and

(b) an ion sulfonate salt represented by Formula III:

    RO(R.sub.1- O).sub.p (CH.sub.2).sub.r SO.sub.3 M           III

or represented by Formula IV:

    MSO.sub.3 (CH.sub.2).sub.s O(R.sub.1 O).sub.p (CH.sub.2).sub.r SO.sub.3 MIV

where M, R and R₁ are as defined above and r and s are independentlyintegers from 2 to 6; and `(c) mixtures of the above.

Preferably, the solid polymeric matrix is an organic matrix derived froma solid matrix forming monomer or partial polymer thereof.

In yet another of its composition aspects, the present invention isdirected to a solid, single phase, solvent-containing electrolyte whichcomprises:

a solvent comprising about a 10:1 to 1:4 mixture of an organic carbonateand a glyme; and

a solid polymeric matrix, said matrix including an ionically conductingnumber of repeating units of an ion salt derivative selected from thegroup consisting of: ##STR1## and combinations thereof, wherein R₅ andR₆ are independently selected from the group consisting of hydrogen andalkyl of from 1 to 4 carbon atoms and M is a metal ion selected from thegroup consisting of Li, Na, K and Mg.

In one of its method aspects, the present invention is directed to amethod for enhancing the cumulative capacity of an electrolytic cellwhich comprises employing the solid, single- phase, solvent-containingelectrolyte described above in the electrolytic cell.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As noted above, this invention is directed to solid, solvent-containingelectrolytes which, by virtue of the ion salt derivative employed,provide for higher purity in the electrolyte and lower electrolytemanufacturing costs. The reduction of impurities also provides forenhanced capacity of the solid battery. However, prior to describingthis invention in further detail, the following terms will first bedefined.

Definitions

As used herein, the following terms have the following meanings.

The term "solid polymeric matrix" refers to an electrolyte compatiblematerial formed by polymerizing an inorganic or organic monomer (orpartial polymer thereof) and which, when used in combination with theother components of the electrolyte, renders the electrolyte solid. Thesolid matrix may or may not be ion-conducting.

Suitable solid polymeric matrices are well known in the art and includesolid matrices formed from inorganic polymers, organic polymers or amixture of organic polymers with inorganic non- polymeric materials.Preferably, the solid polymeric matrix is an organic matrix derived froma solid matrix forming monomer and/or from partial polymers of a solidmatrix forming monomer.

Alternatively, the solid polymeric matrix can be used in combinationwith a non-polymeric inorganic matrix. See, for example, U.S. Pat. No.4,990,413, which is incorporated herein by reference in its entirety.Suitable non-polymeric inorganic materials for use in conjunction withthe solid polymeric matrix include, by way of example, β-alumina, silveroxide, lithium iodide, and the like. Suitable inorganic monomers arealso disclosed in U.S. Pat. Nos. 4,247,499; 4,388,385; 4,414,607;4,394,280; 4,432,891; 4,539,276; and 4,557,985 each of which isincorporated herein by reference.

The term "a solid matrix forming monomer" refers to inorganic or organicmaterials which in monomeric form can be polymerized, preferably in thepresence of the ion salt derivative of the invention and optionally aninorganic ion salt, and a solvent mixture of an organic carbonate and aglyme compound, to form solid matrices which are suitable for use assolid electrolytes in electrolytic cells. Suitable solid matrix formingmonomers are well known in the art and the particular monomer employedis not critical. Preferably, the solid matrix forming monomers have atleast one heteroatom capable of forming donor acceptor bonds withinorganic cations (e.g., alkali ions). When polymerized, such compoundsform an ionically conductive matrix.

Examples of suitable organic solid matrix forming monomers include, byway of example, propylene oxide, ethyleneimine, ethylene oxide,epichlorohydrin, acryloyl-derivatized polyalkylene oxides (as disclosedin U.S. Pat. No. 4,908,283), vinyl sulfonate polyalkylene oxides (asdisclosed in U.S. Pat. No. 5,262,255, which patent is incorporatedherein by reference in its entirety), and the like as well as mixturesthereof. Ethylene oxide is especially preferred.

Examples of suitable inorganic solid matrix forming monomers include, byway of example, phosphazenes and siloxanes. Phosphazene monomers and theresulting polyphosphazene solid matrix are disclosed by Abraham et al.,Proc. Int. Power Sources Symp., 34th, pp. 81-83 (1990) and by Abraham etal., J. Electrochemical Society, Vol. 138, No. 4, pp. 921-927 (1991) .

In one embodiment of the invention an ion salt derivative is formed byforming one or more terminal hydroxy groups on a solid matrix-formingorganic monomer and thereafter reacting with an organometallic compound.The ion salt is then incorporated as a pendant group from the polymerbackbone. The monomer having the ion salt incorporated therein need notcontain a heteroatom but preferably the matrix includes other monomerscontaining a heteroatom.

The term "a partial polymer of a solid matrix forming monomer" refers tosolid matrix forming monomers which have been partially polymerized toform reactive oligomers. Partial polymerization may be conducted for thepurpose of enhancing the viscosity of the monomer, decreasing thevolatility of the monomer, and the like. Partial polymerization isgenerally permitted so long as the resulting partial polymer can befurther polymerized, preferably in the presence of a solvent mixture ofan organic carbonate and a glyme compound and optionally an ion saltderivative of Formulae I to IV above, to form solid polymeric matriceswhich are suitable for use as solid electrolytes in electrolytic cells.

The term "cured" or "cured product" refers to the treatment of the solidmatrix forming monomer or partial polymer thereof under polymerizationconditions (including cross-linking) so as to form a solid polymericmatrix. Suitable polymerization conditions are well known in the art andinclude by way of example, heating the monomer, irradiating the monomerwith UV light, electron beams, etc. The resulting cured productpreferably contains repeating units containing at least one heteroatomsuch as oxygen or nitrogen which is capable of forming donor acceptorbonds with inorganic cations (e.g., alkali ions). Examples of suitablecured products suitable for use in this invention are set forth in U.S.Pat. Nos. 4,830,939 and 4,990,413 which are incorporated herein byreference in their entirety.

The solid matrix forming monomer or partial polymer can be cured orfurther cured prior to or after addition of the solvent. For example, acomposition comprising requisite amounts of the solid matrix formingmonomer and organic carbonate/glyme/ion salt derivative forming thesolvent can be applied to a substrate and then cured. Alternatively, thesolid matrix forming monomer can be first cured and then dissolved intoa suitable volatile solvent. Requisite amounts of the organiccarbonate/glyme/ion salt derivative solvent can then be added. Themixture is then placed on a substrate and removal of the volatilesolvent results in formation of a solid electrolyte. In either case, theresulting solid electrolyte is a homogeneous, single phase product whichis maintained upon curing, and does not readily separate upon cooling totemperatures below room temperature. Accordingly, the solid electrolyteof this invention does not include a separator as is typical of liquidelectrolytes.

The term "inorganic ion salt" refers to any inorganic salt which issuitable for use in a solid electrolyte. Representative examples arealkali metal salts of less mobile anions of weak bases having a largeanionic radius. Examples of such anions are I⁻, Br⁻, SCN⁻, ClO₄, BF₄ ⁻,PF₆ ⁻, AsF₆ ⁻, CF₃ COO⁻, CF₃ SO₃ ⁻, etc. Specific examples of suitableinorganic ion salts include LiClO₄, LiI, LiSCN, LiBF₄, LiAsF₆, LiCF₃SO₃, LiPF₆, NaI, NaSCN, KI, and the like. The inorganic ion saltpreferably contains at least one atom of Li, Na, K or Mg.

The term "ion salt derivative" refers to the reaction product of eitheran alkylene glycol(ether) (which includes at least one terminal hydroxylgroup) or a monomer having a polymerizable moiety such as a double bond,cyclic ether, etc., and which also includes at least one terminalhydroxyl group. The alkylene glycol(ether) or the monomer is thenreacted with an organometallic compound in which the metal is Li, Na, Kor Mg. The reaction replaces the hydroxyl group(s) with the metal toform the ion salt derivative. Suitable organometal compounds includethose having the formula MR₇ where M is Li, Na, K or Mg, and R₇ is analkyl group of from 1 to 6 carbon atoms. Lithium is preferred as themetal and in a highly preferred embodiment the organometal is n-butyllithium. Alternative methods of attaching the metal ion may also beemployed.

The term "organic carbonate" refers to hydrocarbyl carbonate compoundsof no more than about 12 carbon atoms and which do not contain anyhydroxyl groups. Preferably, the organic carbonate is a linear aliphaticcarbonate or a cyclic aliphatic carbonate.

In a more preferred embodiment, the carbonate is a cyclic aliphaticcarbonate represented by the formula: ##STR2## where each of R₈, R₉,R₁₀, R₁₁, R₁₂, and R₁₃ are independently selected from the groupconsisting of hydrogen and alkyl of 1 or 2 carbon atoms, and m is aninteger equal to 0 or 1.

In a particularly preferred embodiment, m is equal to zero and R₈, R₉,and R₁₂ are hydrogen and R₁₃ is hydrogen (ethylene carbonate), --CH₃(propylene carbonate) or --CH₂ CH₃ (butylene carbonate).

Suitable cyclic aliphatic carbonates for use in this invention include1,3-dioxolan-2-one (ethylene carbonate); 4-methyl-l,3-dioxolan-2-one(propylene carbonate); 4,5-dimethyl-l,3-dioxolan-2-one;4-ethyl-l,3-dioxolan-2-one; 4,4-dimethyl-1,3-dioxolan-2-one;4-methyl-5-ethyl-1,3-dioxolan-2-one; 4,5-diethyl-1,3-dioxolan-2-one;4,4-diethyl-1,3-dioxolan-2-one; 1,3-dioxan-2-one;4,4-dimethyl-1,3-dioxan-2-one; 5,5-dimethyl-1,3-dioxan-2-one;5-methyl-1,3-dioxan-2-one; 4-methyl-1,3-dioxan-2-one;5,5-diethyl-1,3-dioxan-2-one; 4,6-dimethyl-1,3-dioxan-2-one;4,4,6-trimethyl-1,3-dioxan-2-one; and spiro [1,3-oxa-2-cyclohexanone-5',5',1',3'-oxa-2'-cyclohexanone].

Several of these cyclic aliphatic carbonates are commercially availablesuch as propylene carbonate and ethylene carbonate. Alternatively, thecyclic aliphatic carbonates can be readily prepared by well knownreactions. For example, reaction of phosgene with a suitablealkane-α,β-diol (dihydroxy alkanes having hydroxyl substituents onadjacent carbon atoms) or an alkane-α,γ-diol (dihydroxy alkanes havinghydroxyl substituents on carbon atoms in a 1,3 relationship) yields an acyclic aliphatic carbonate for use within the scope of this invention.See, for instance, U.S. Pat. No. 4,115,206, which is incorporated hereinby reference in its entirety.

Likewise, the cyclic aliphatic carbonates useful for this invention maybe prepared by transesterification of a suitable alkane-α,β-diol or analkane-α,γ-diol with, e.g., diethyl carbonate under transesterificationconditions. See, for instance, U.S. Pat. Nos. 4,384,115 and 4,423,205which are incorporated herein by reference in their entirety.

Additional suitable cyclic aliphatic carbonates are disclosed in U.S.Pat. No. 4,747,850 which is also incorporated herein by reference in itsentirety.

In a more preferred embodiment, linear aliphatic carbonates arerepresented by the formulae:

    R.sub.14 [OC(O)].sub.t OR.sub.15 and R.sub.14 [OC(O)R.sub.16 ].sub.u OC(O)R.sub.15

where each R₁₄ and R₁₅ are independently selected from the groupconsisting of alkyl of from 1 to 4 carbon atoms; R₁₆ is an alkylenegroup of from 2 to 4 carbon atoms; t is an integer of 1 or 2, and u isan integer from 1 to 4.

Most preferably, the linear aliphatic carbonate is a carbonate of theformula:

    R.sub.14 [OC(O)].sub.t OR.sub.15

where R₁₄, R₁₅ and t are as defined above.

Linear aliphatic carbonates are well known in the art and a variety ofwhich are commercially available. Additionally, the linear aliphaticcarbonates can be prepared by transesterification of a suitable alcohol(e.g., R₁₄ OH or R₁₅ OH) with, e.g., diethyl carbonate undertransesterification conditions.

The term "sultone refers to a cyclic sulfone having the formula ##STR3##wherein x is an integer from 2 to 6, preferably 3 or 4. The ion saltderivative can be reacted with a sultone to form a sulfonate saltderivative of Formula III or IV. Where the ion salt derivative is adisalt, both salt moieties are preferably reacted with a sultone.

The term "alkylene glycol(ether)" refers to a glycol or glycol etherhaving at least one terminal hydroxyl group. In forming the ion saltderivative from the alkylene glycol(ether), the alkylene glycol(ether)is reacted with the organometal compound defined above. In general, thealkylene glycol(ether) has the formula HO(R₁ O)_(p) OH or the formulaR(R₁ O)_(p) OH where R, R₁ and p are as defined above, or where R and R₁are as defined above.

The term "glyme" refers to ethylene glycol dimethyl ether or CH₃ OCH₂CH₂ OCH₃. The term "a glyme" refers to glyme and also to diglyme,triglyme, tetraglyme, etc., which contain repeating units of --(OCH₂CH₂)--.

The term "an alkylene glycol(ether) derivative" refers to the ion saltderivative formed from the corresponding alkylene glycol(ether).

The term "electrolytic cell" refers to a composite containing an anode,a cathode and an ion-conducting electrolyte interposed therebetween.

The anode is typically comprised of a compatible anodic material whichis any material which functions as an anode in a solid electrolyticcell. Such compatible anodic materials are well known in the art andinclude, by way of example, lithium, lithium alloys such as alloys oflithium with aluminum, mercury, tin, zinc, and the like, andintercalation based anodes such as carbon, tungsten oxides and the like.

The cathode is typically comprised of a compatible cathodic material(i.e., insertion compounds) which is any material which functions as apositive pole in a solid electrolytic cell. Such compatible cathodicmaterials are well known in the art and include, by way of example,manganese oxides, molybdenum oxides, vanadium oxides, sulfides oftitanium and niobium, lithiated cobalt oxides, the various lithiatedmanganese oxides, chromium oxides, copper oxides, and the like. Theparticular compatible cathodic material employed is not critical.

In one preferred embodiment, the compatible cathodic material is mixedwith an electroconductive material including, by way of example,graphite, powdered carbon, powdered nickel, metal particles,electronically conductive polymers (i.e., characterized by a conjugatednetwork of double bonds like polypyrrole, polyacetylene, polyaniline andpolythiophene and the like), and a binder, such as a polymeric binder,to form under pressure a positive cathodic plate.

In another preferred embodiment, the cathode is prepared from a cathodepaste which comprises from about 35 to 65 weight percent of a compatiblecathodic material; from about 1 to 20 weight percent of anelectroconductive agent; from about 0 to 20 weight percent ofpolyethylene oxide having a number average molecular weight of at least100,000; from about 10 to 50 weight percent of solvent comprising a 10:1to 1:4 (w/w) mixture of an organic carbonate and a glyme; and from about5 weight percent to about 25 weight percent of a solid matrix formingmonomer or partial polymer thereof. Also included is an ion conductingamount of the ion salt derivative of Formulae I to IV. Generally, theamount of the derivative is from about 1 to about 25 weight percent.(All weight percents are based on the total weight of the cathode.)

In yet another preferred embodiment, the cathode paste is formed asabove except that the ion salt derivative is formed by reaction with asolid matrix forming monomer or partial polymer thereof rather than, orin addition to, reaction with an alkylene glycol(ether). In thisembodiment, an ion conducting amount of the ion salt derivative isincorporated into matrix. Generally, the ion salt derivative comprisesfrom about 1 to about 50 percent of the monomers (i.e., repeating unitsin the matrix) and preferably between about 15 and 30 percent.

The cathode paste is typically spread onto a suitable support such as acurrent collector and then cured by conventional methods to provide fora solid positive cathodic plate. The cathode (excluding the support)generally has a thickness of about 20 to about 150 microns.

Current collectors are well known in the art some of which arecommercially available. One particularly preferred current collector forthe cathode is a roughened nickel (electrolytically deposited nickel) onnickel current collector (available as CF18/NiT from Fukuda Metal Foil &Powder Company, Ltd., Kyoto, Japan). Another preferred current collectoremploys a sheet of aluminum foil. The current collector is preferablyattached to the surface of the cathode not facing the electrolyte butcan also be attached to the anode. When the current collector isattached to the cathode, the cathode is interposed between theelectrolyte and the current collector.

In still another preferred embodiment, the electrolyte solvent and thecathode solvent are identical.

The term "urethane acrylate" refers to urethane diacrylate.

Methodology

Methods for preparing solid, solvent-containing electrolytes are wellknown in the art. In one embodiment, however, this invention utilizes aparticular solvent (plasticizer) mixture in the preparation of solidelectrolytes which solvent mixture provides improvements in electrolytemanufacture and economics.

In another embodiment, this invention employs an ion salt derivativeformed from a solid matrix forming monomer or other polymerizablemonomer which is incorporated into the polymer matrix.

As noted above, organic carbonates are either commercially available orcan be prepared by art recognized methods. Similarly, alkyleneglycol(ethers) which can be reacted to form the derivatives of FormulaeI and II above are also either commercially available or can be preparedby art recognized methods. For example, the preparation of RO(CR₃ R₄ CR₃R₄)_(p) OH compounds, where R, R₃, R₄, and p are as defined above, canbe readily prepared by reaction of an ethylene oxide derivative [anoxide derived from CR₃ R₄ ═CR₃ R₄ by conventional methods] with ROHunder polymerization conditions. See, for example, U.S. Pat. No.4,695,291 which is incorporated herein by reference.

Careful control of the stoichiometry, e.g., 3 moles of the ethyleneoxide derivative to 1 mole of ROH when p=3, and reaction conditions willresult in formation of a mixture of oligomers of the formula RO(CR₃ R₄CR₃ R₄ O)_(p) OH wherein the mixture will contain a substantial amountof the trimer (p=3) as well as other oligomers such as the dimer andtetramer etc. (i.e., p=2, p=4, etc.). The trimer can then be separatedfrom the reaction mixture by conventional methods includingdistillation, column chromatography, high performance liquidchromatography (HPLC), and the like. The resulting hydroxy-terminatedoligomers are then reacted with an organometallic compound such ast-butyl lithium to form the corresponding alkylene glycol(ether)derivative.

In addition to the alkylene glycol(ether) derivative, the solventincludes a glyme which can be formed by alkylation of the correspondingethylene glycol ether. Such alkylation can be readily accomplished byknown methods including, by way of example, treatment of the alkyleneglycol(ether) with metallic sodium followed by addition of RCl, where Ris as defined above.

The solid, solvent-containing electrolyte is then preferably prepared bycombining one or more solid matrix-forming monomers and the solventwherein either one or both the solid matrix-forming monomers and thesolvent include an ion salt derivative as defined above. The resultingcomposition is then uniformly coated onto a suitable substrate (e.g.,aluminum foil, a glass plate, a lithium anode, a cathode, etc.) by meansof a roller, a doctor blade, a bar coater, a silk screen or spinner toobtain a film of this composition or its solution. In some cases, it maybe necessary to heat the composition so as to provide for a coatablematerial.

Preferably, the amount of material coated onto the substrate is anamount sufficient so that after curing, the resulting solid,solvent-containing electrolyte has a thickness of no more than about 250microns (μm). Preferably, the solid, solvent-containing electrolyte mayhave a thickness of from about 20 to about 250 microns. The finalthickness will depend on the particular application.

The electrolyte composition typically comprises from about 5 to about 25weight percent of the ion salt derivative based on the total weight ofthe electrolyte; preferably, from about 10 to 20 weight percent; andeven more preferably from about 10 to about 15 weight percent.

The electrolyte composition typically comprises from about 40 to about80 weight percent solvent (i.e., organic carbonate/glyme mixture) basedon the total weight of the electrolyte; preferably from about 60 toabout 80 weight percent; and even more preferably about 70 weightpercent.

The solid electrolyte composition typically comprises from about 5 toabout 30 weight percent of the solid polymeric matrix based on the totalweight of the electrolyte; preferably from about 15 to about 25 weightpercent.

In a preferred embodiment, the ion salt derivative completely replacesthe inorganic ion salt of the prior art. However, partial replacement ofthe salt is also possible. Thus, in another preferred embodiment, lessthan 100%, but at least about 20% by weight of the salt (on a w/w basisfor the same metal cation) is replaced by the ion salt derivative.

In a preferred embodiment, the electrolyte composition further comprisesa small amount of a film forming agent. Suitable film forming agents arewell known in the art and include, by way of example, polyethyleneoxide, polypropylene oxide, copolymers thereof, and the like, having anumbered average molecular weight of at least about 100,000. Preferably,the film forming agent is employed in an amount of about 1 to about 10weight percent and more preferably at about 2.5 weight percent based onthe total weight of the electrolyte composition.

The composition is cured by conventional methods to form a solid film.For example, when the solid matrix forming monomer contains a reactivedouble bond, suitable curing methods include heating, irradiation withUV radiation, irradiation with electron beams (EB), etc. When thecomposition is cured by heating or UV radiation, the compositionpreferably contains an initiator. For example, when curing is byheating, the initiator is typically a peroxide such as benzoyl peroxide,methyl ethyl ketone peroxide, t-butyl peroxypyvarate, diisopropylperoxycarbonate, and the like. When curing is by UV radiation, theinitiator is typically benzophenone, Darocur 1173 (Geigy, Ardsley,N.Y.), and the like.

The initiator is generally employed in an amount sufficient to catalyzethe polymerization reaction. Preferably, the initiator is employed at upto about 1 weight percent based on the weight of the solid matrixforming monomer.

When curing is by EB treatment, an initiator is not required.

The resulting solid electrolyte is a homogeneous, single phase materialwhich is maintained upon curing, and does not readily separate uponcooling to temperatures below room temperature. See, for example, U.S.Pat. No. 4,925,751 which is incorporated herein by reference in itsentirety.

Additionally, it is desirable to avoid the use of any protic materialswhich will be incorporated into the battery. For example, most of theprotic inhibitors in mono-, di-, tri- and higher functional acrylatemonomers as well as in the urethane acrylate prepolymers, are preferablyremoved prior to formation of the cathode and/or electrolyte. In thisregard, removal of these inhibitors down to a level of less than 50parts per million (ppm) can be accomplished by contacting these monomersand prepolymers with an inhibitor remover. Suitable inhibitor removersare commercially available.

In a preferred embodiment, the process of forming an electrolytic cellcomprises the steps of coating the surface of a cathode with acomposition comprising at least one solid matrix forming monomer, aninorganic ion salt (if present) and the solvent mixture of an organiccarbonate and a glyme compound together with an ion salt derivative ofFormulae I-IV. The composition is then cured to provide for a solidelectrolyte on the cathodic surface. The anode (e.g., a lithium foil) isthen laminated to this composite product in such a way that the solidelectrolyte is interposed between the lithium foil and the cathodicmaterial.

This process can be reversed, so that the surface of the anode is coatedwith a composition comprising a solid matrix forming monomer, thesolvent mixture of an organic carbonate, glyme and an ion saltderivative of Formulae I to IV. The composition is then cured to providefor a solid electrolyte on the anodic surface. The cathode is thenlaminated to this composite product in such a way that the solidelectrolyte is interposed between the lithium foil and the cathodicmaterial.

Methods for preparing solid electrolytes and electrolytic cells are alsoset forth in U.S. Pat. Nos. 4,830,939 and 4,925,751 which areincorporated herein by reference in their entirety.

Utility

The solid, solvent-containing electrolytes described herein areparticularly useful in preparing solid electrolytic cells which are freeof contamination by impurities from inorganic ion salt decomposition. Inaddition to reduced contamination from impurities, when all or part ofthe requisite ion salt is incorporated into the polymer matrix of theelectrolyte, the charge transference is increased, resulting in improvedcumulative capacity compared to solid, solvent-containing electrolytesin which only an inorganic ion salt is present.

The following examples are offered to illustrate the present inventionand should not be construed in any way as limiting its scope.

EXAMPLE 1

A. The Cathode

The cathode may be prepared from a cathodic paste which, in turn, isprepared from a cathode powder as follows:

i. Cathode Powder

The cathode powder is prepared by combining 90.44 weight percent V₆ O₁₃[prepared by heating ammonium metavanadate (NH₄ ⁺ VO₃ ⁻) at 450° C. for16 hours under N2 flow] and 9.56 weight percent of carbon (from ChevronCompany, San Ramon, Calif. under the trade name of Shawinigan Black®).About 100 grams of the resulting mixture is placed into a grindingmachine (Attritor Model S-1 purchased from Union Process, Akron, Ohio)and ground for 45 minutes. Afterwards, the resulting mixture is dried atabout 260° C for 16 hours under vacuum to provide a cathode powderhaving about 84.45 weight percent V₆ O₁₃.

The above mixing procedure is repeated to provide for a total of 292grams of cathode powder.

ii. Cathode Paste

A cathode paste may be prepared by combining sufficient cathode powderto provide for a final product having 45 weight percent V₆ O₁₃.

Specifically, about 26.2 grams of unground carbon (from Chevron ChemicalCompany, San Ramon, Calif. under the trade name of Shawinigan Black®) iscombined in a glove box [under dry (<10 ppm H₂ O) argon at ambienttemperature and pressure] with about 169.9 grams of a 4:1 w/w mixture ofpropylene carbonate/triglyme and the resulting composite is mixed underdry argon and at ambient temperature and pressure on a double planatorymixer (Ross #2 mixer available from Charles Ross & Sons, Company,Hauppag, N.Y.) at about 25 rpms until a paste is formed.

About 225.0 grams of a cathode powder prepared in a manner similar tothat described above is added to the mixer and the resulting compositeis mixed under dry argon and at ambient temperature and pressure on adouble planatory mixer at about 25 rpms until a dry paste is formed.

About 5 grams of polyethylene oxide (number average molecular weightabout 600,000 available as Polyox WSR-205 from Union Carbide Chemicalsand Plastics, Danbury, Conn.), about 42.5 grams of polyethylene glycoldiacrylate (molecular weight about 400 available as SR-344 from SartomerCompany, Inc., Exton, Pa.) and containing less than about 50 ppm ofinhibitor, and about 7.5 grams of ethoxylated trimethylpropanetriacrylate (TMPEOTA) (molecular weight about 450 available as SR-454from Sartomer Company, Inc., Exton, Pa.) and containing less than about50 ppm of inhibitor are added to about 169.9 grams of a 4:1 mixture ofpropylene carbonate/triglyme as described above and this mixture thenadded to the mixer.

The resulting slurry in the mixer is heated at about 65° C. while mixingfor 2 hours at 60 rpms to provide for the cathodic paste which wouldhave the following approximate weight percent of components:

    ______________________________________                                        V.sub.6 O.sub.13  percent 45.00 weight                                        Carbon percent            10.00 weight                                        Propylene carbonate percent                                                                             27.18 weight                                        Triglyme percent          6.80 weight                                         Polyethylene glycol diacrylate percent                                                                  8.51 weight                                         Ethoxylated trimethylpropane triacrylate.sup.1 percent                                                  1.51 weight                                         Polyethylene oxide percent                                                                              1.00 weight                                         ______________________________________                                         .sup.1 Inhibitor may be removed from both the polyethylene glycol             diacrylate and ethoxylated trimethylpropane triacrylate by contacting eac     of these compounds with an Inhibitor Remover available as Product No.         31,1332 from Aldrich Chemical, Milwaukee, Wisconsin, which results in les     than 50 ppm of inhibitor in the product.                                 

In an alternative embodiment, the requisite amounts of all of thecathodic materials other than the cathode powder can be combined to forma first mixture and this first mixture is combined with the cathodepowder to form a second mixture. This second mixture is then thoroughlymixed to provide for the cathode paste.

The cathode paste prepared as above is placed onto a sheet [about 1 mil(N-25 μm) thick by 10 cm wide] of a roughened nickel on nickel currentcollector (available as CF18/NiT from Fukuda Metal Foil & PowderCompany, Ltd., Kyoto, Japan). A Mylar cover sheet is then placed overthe paste and the paste is spread to a thickness of about 75 microns(μm) with a conventional plate and roller system and cured bycontinuously passing the sheet through an electron beam apparatus(Electrocurtain, Energy Science Inc., Woburn, Mass.) at a voltage ofabout 175 kV and a current of about 12 mA and at a conveyor belt speedsetting of 50 which provides a conveyor speed of about 3 in/sec. Aftercuring, the Mylar sheet is removed to provide for a solid cathodelaminated to a nickel on nickel current collector.

B. Electrolyte

The electrolyte may be prepared by first combining 56.51 grams ofpropylene carbonate, 14.13 grams triglyme and 17.56 grams of urethaneacrylate (available as Photomer 6140 from Henkel Corporation, Coatingand Chemicals Division, Ambler, Pa.). The propylenecarbonate/triglyme/urethane acrylate mixture is dried over molecularsieves (Grade 514, 4 Å, 8-12 mesh, available from W. R. Grace,Baltimore, Md.) to remove water.

This solution is then combined with 2.56 grams of poly- ethylene oxide(weight average molecular weight about 600,000 available as PolyoxWSR-205 from Union Carbide Chemicals and Plastics, Danbury, Conn.). Themixture is then thoroughly mixed with the same laboratory mixer atheating until a temperature of about 65° C. is reached and then cooledto ambient temperature over at least a 2 hour period while stirring ismaintained.

Once the polyethylene oxide is dispersed and dissolved, 4.24 grams ofLiAsF₆ (available from FMC Corporation Lithium Division, Bessemer City,N.C., as Lectrosalt®) and 5.00 grams of Li(OCH₂ CH₂)₃ OCH₃ are addedwhile stirring with a laboratory mixer (Yamato Model LR41B, availablefrom Fisher Scientific, Santa Clara, Calif.). The Li(OCH₂ CH₂)₃ OCH₃salt can be prepared from a 1:1 molar ratio n-butyl lithium and themonomethylether of triethylene glycol in tetrahydrofuran at -78° C.Other aprotic solvents could also be used.

The resulting 100 gram mixture would contain the following weightpercent of components:

    ______________________________________                                        Propylene carbonate percent                                                                          56.51 weight                                           Triglyme percent       14.13 weight                                           Urethane acrylate (Photomer 6140) percent                                                            17.56 weight                                           LiAsF.sub.6  percent    4.24 weight                                           Li(OCH.sub.2 CH.sub.2).sub.3 OCH.sub.3  percent                                                       5.00 weight                                           Polyethylene oxide percent.                                                                           2.56 weight                                           ______________________________________                                    

Afterwards, the electrolyte mixture is then coated by a conventionalknife blade to a thickness of about 50 μm onto the surface of thecathode sheet prepared as above (on the side opposite that of thecurrent collector) but without the Mylar covering. The electrolyte isthen cured by continuously passing the sheet through an electron beamapparatus (Electrocurtain, Energy Science Inc., Woburn, Mass.) at avoltage of about 175 kV and a current of about 1.0 mA and at a conveyorspeed setting of 50 which provides for a conveyor speed of about 1cm/sec. After curing, a composite is recovered which contains a solidelectrolyte laminated to a solid cathode which, in turn, is laminated toa nickel on nickel current collector.

C. Anode

The anode may comprise a sheet of lithium foil (about 76 μm thick) whichis commercially available from FMC Corporation Lithium Division,Bessemer City, N.C.

D. The Solid Battery

A solid battery may be prepared by first preparing a cathodic paste asdescribed above which is spread onto a substrate (e.g., a currentcollector) and then cured to provide the cathode. An electrolytecomposition as described above is then placed onto the cathode surfaceand cured to provide for the solid electrolyte. Then, the anode islaminated onto the solid electrolyte to provide for the solid battery.

EXAMPLES 2-6

Additional solid batteries may be prepared in a manner similar to thatof Example 1 except that the alkylene glycol(ether) derivative Li(OCH₂CH₂)₃ OCH₃ is replaced by Li(OCH₂ CH₂)₃ OLi (Example 2 ) , CH₃ (OCH₂CH₂)₃ O(CH₂)₃ SO₃ Li (Example 3) , CH₃ (OCH₂ CH₂)₃ O(CH₂)₄ SO₃ Li(Example 4 ) , LiO₃ S(CH₂)₃ (OCH₂ CH₂)₃ O(CH₂)₃ SO₃ Li (Example 5) andLiO₃ S(CH₂)₄ (OCH₂ CH₂)₃ O(CH₂)₄ SO₃ Li (Example 6). In each of Examples2-6, the amount of the ion salt derivative added provides an amount oflithium equivalent to that provided in Example 1.

The Li(OCH₂ CH₂)₃ OLi salt may be prepared from a 1:1 molar ration-butyl lithium and triethylene glycol in an aprotic solvent such astetrahydrofuran at -78° C. The sultone salts may be prepared by reactingthe Li salts (in the correct molar ratio, i.e., 1 mole of the sultonewith the monolithium salt, and two moles of the sultone with thedilithium salt) listed above with 1,4-butane, n=4, (or 1,3-propane, n=3)sultone in an aprotic solvent such as tetrahydrofuran at -78° C.

EXAMPLE 7

A solid electrolytic cell is prepared by first preparing a cathodicpaste which is spread onto a current collector and is then cured toprovide for the cathode. An electrolyte solution is then placed onto thecathode surface and is cured to provide for the solid electrolytecomposition. Then, the anode is laminated onto the solid electrolytecomposition to provide for a solid electrolytic cell. The specifics ofthis construction are as follows:

A. The Current Collector

The current collector employed is a sheet of aluminum foil having alayer of adhesion promoter attached to the surface of the foil whichwill contact the cathode so as to form a composite having a sheet ofaluminum foil, a cathode and a layer of adhesion promoter interposedtherebetween.

Specifically, the adhesion promoter layer is prepared as a dispersedcolloidal solution in one of two methods. The first preparation of thiscolloidal solution for this example is as follows:

84.4 weight percent of carbon powder (Shawinigan Black®--available fromChevron Chemical Company, San Ramon, Calif.)

337.6 weight percent of a 25 weight percent solution of polyacrylic acid(a reported average molecular weight of about 90,000, commerciallyavailable from Aldrich Chemical Company--contains about 84.4 gramspolyacrylic acid and 253.2 grams water)

578.0 weight percent of isopropanol

The carbon powder and isopropanol are combined with mixing in aconventional high shear colloid mill mixer (Ebenbach-type colloid mill)until the carbon is uniformly dispersed and the carbon particle size issmaller than 10 microns. At this point, the 25 weight percent solutionof polyacrylic acid is added to the solution and mixed for approximately15 minutes. The resulting mixture is pumped to the coating head and rollcoated with a Meyer rod onto a sheet of aluminum foil (about 9 incheswide and about 0.0005 inches thick). After application, thesolution/foil are contacted with a Mylar wipe (about 0.002 inches thickby about 2 inches and by about 9 inches wide--the entire width ofaluminum foil). The wipe is flexibly engaged with the foil (i.e., thewipe merely contacted the foil) to redistribute the solution so as toprovide for a substantially uniform coating. Evaporation of the solvents(i.e., water and isopropanol) via a conventional gas-fired oven providesfor an electrically-conducting adhesion-promoter layer of about 6microns in thickness or about 3×104 grams per cm². The aluminum foil isthen cut to about 8 inches wide by removing approximately 1/2 inch fromeither side by the use of a conventional slitter so as to remove anyuneven edges.

In order to further remove the protic solvent from this layer, the foilis redtied. In particular, the foil is wound up and a copper supportplaced through the roll's cavity. The roll is then hung overnight fromthe support in a vacuum oven maintained at about 130° C. Afterwards, theroll is removed. In order to avoid absorption of moisture from theatmosphere, the roll is preferably stored into a desiccator or othersimilar anhydrous environment to minimize atmospheric moisture contentuntil the cathode paste is ready for application onto this roll.

The second preparation of this colloidal solution comprises mixing 25lbs of carbon powder (Shawinigan Black®--available from Chevron ChemicalCompany, San Ramon, Calif.) with 100 lbs of a 25 weight percent solutionof polyacrylic acid (average molecular weight of about 240,000,commercially available from BF Goodrich, Cleveland, Ohio, as Good-RiteK702--contains about 25 lbs polyacrylic acid and 75 lbs water) and with18.5 lbs of isopropanol. Stirring is done in a 30 gallon polyethylenedrum with a gear-motor mixer (e.g., Lightin Labmaster Mixer, modelXJ-43, available from Cole-Parmer Instruments Co., Niles, Ill.) at 720rpm with two 5 inch diameter A310-type propellers mounted on a singleshaft. This wets down the carbon and eliminates any further dustproblem. The resulting weight of the mixture is 143.5 lbs and containssome "lumps".

The mixture is then further mixed with an ink mill which consists ofthree steel rollers almost in contact with each other, turning at 275,300, and 325 rpms respectively. This high shear operation allowsparticles that are sufficiently small to pass directly through therollers. Those that do not pass through the rollers continue to mix inthe ink mill until they are small enough to pass through these rollers.When the mixing is complete, the carbon powder is completely dispersed.A Hegman fineness of grind gauge (available from Paul N. Gardner Co.,Pompano Beach, Fla.) indicates that the particles are 4-6 μm with theoccasional 12.5 μm particles. The mixture can be stored for well over 1month without the carbon settling out or reagglomerating.

When this composition is to be used to coat the current collector, anadditional 55.5 lbs of isopropanol is mixed into the composition workingwith 5 gallon batches in a plastic pail using an air powered shaft mixer(Dayton model 42231 available from Granger Supply Co., San Jose, Calif.)with a 4 inch diameter Jiffy-Mixer brand impeller (such as an impelleravailable as Catalog No. G-04541-20 from Cole Parmer Instrument Co.,Niles, Ill.). Then, it is gear pumped through a 25 μm cloth filter(e.g., So-Clean Filter Systems, American Felt and Filter Company,Newburgh, N.Y.) and Meyer-rod coated as described above.

B. The Cathode

The cathode is prepared from a cathodic paste which, in turn, isprepared from a cathode powder as follows:

i. Cathode Powder

The cathode powder is prepared by combining 90.44 weight percent V₆ O₁₃[prepared by heating ammonium metavanadate (NH₄ +VO₃ ⁻) at 450° C. for16 hours under N₂ flow] and 9.56 weight percent of carbon (from ChevronChemical Company, San Ramon, Calif. under the tradename of ShawiniganBlack®). About 100 grams of the resulting mixture is placed into agrinding machine (Attritor Model S-1 purchased from Union Process,Akron, Ohio) and ground for 30 minutes. Afterwards, the resultingmixture is dried at about 260° C. for 21 hours.

ii. Cathode Paste

A cathode paste is prepared by combining sufficient cathode powder toprovide for a final product having 45 weight percent V₆ O₁₃.

Specifically, 171.6 grams of a 4:1 weight ratio of propylenecarbonate:triglyme is combined with 42.9 grams of polyethylene glycoldiacrylate (molecular weight about 400 available as SR-344 from SartomerCompany, Inc., Exton, Pa.), and about 7.6 grams of ethoxylatedtrimethylpropane triacrylate (TMPEOTA) (molecular weight about 450available as SR-454 from Sartomer Company, Inc., Exton, Pa.) in a doubleplanetary mixer (Ross #2 mixer available from Charles Ross & Sons,Company, Hauppag, N.Y.).

A propeller mixture is inserted into the double planetary mixer and theresulting mixture is stirred at a 150 rpms until homogeneous. Theresulting solution is then passed through sodiated 4 Å molecular sieves.The solution is then returned to double planetary mixer equipped withthe propeller mixer and about 5 grams of polyethylene oxide (numberaverage molecular weight about 600,000 available as Polyox WSR-205 fromUnion Carbide Chemicals and Plastics, Danbury, Conn.) is added to thesolution vortex from by the propeller by a mini-sieve such as a 25 meshmini-sieve commercially available as Order No. 57333-965 from VWRScientific, San Francisco, Calif.

The solution is then heated while stirring until the temperature of thesolution reaches 65° C. At this point, stirring is continued until thesolution is completely clear. The propeller blade is removed and thecarbon powder prepared as above is then is added as well as anadditional 28.71 grams of unground carbon (from Chevron ChemicalCompany, San Ramon, Calif. under the tradename of Shawinigan Black®).The resulting mixture is mixed at a rate of 7.5 cycles per second for 30minutes in the double planetary mixer. During this mixing thetemperature is slowly increased to a maximum of 73° C. At this point,the mixing is reduced to 1 cycle per second the mixture slowly cooled to40° C. to 48° C. (e.g. about 45° C.). The resulting cathode paste ismaintained at this temperature until just prior to application onto thecurrent collector.

The resulting cathode paste has the following approximate weight percentof components:

    ______________________________________                                        V.sub.6 O.sub.13        45 weight percent                                     Carbon                  10 weight percent                                     4:1 Propylene carbonate/triglyme                                                                      34 weight percent                                     Polyethylene oxide       1 weight percent                                     Polyethylene glycol diacrylate                                                                       8.5 weight percent                                     Ethoxylated trimethylpropane triacrylate                                                             1.5 weight percent.                                    ______________________________________                                    

In an alternative embodiment, the requisite amounts of all of the solidcomponents are added to directly to combined liquid components. In thisregard, mixing speeds can be adjusted to account for the amount of thematerial mixed and size of vessel used to prepare the cathode paste.Such adjustments are well known to the skilled artisan.

In order to enhance the coatability of the carbon paste onto the currentcollector, it may be desirable to heat the paste to a temperature offrom about 60° C. to about 130° C. and more preferably, from about 80°C. to about 90° C. and for a period of time of from about 0.1 to about 2hours, more preferably, from about 0.1 to 1 hour and even morepreferably from about 0.2 to 1 hour. A particularly preferredcombination is to heat the paste at from about 80° C. to about 90° C.for about 0.33 to about 0.5 hours.

During this heating step, there is no need to stir or mix the pastealthough such stirring or mixing may be conducted during this step.However, the only requirement is that the composition be heated duringthis period. In this regard, the composition to be heated has a volumeto surface area ratio such that the entire mass is heated during theheating step.

A further description of this heating step is set forth in U.S. patentapplication Ser. No. 07/968,203 filed Oct. 29, 1992, now abandoned,entitled "METHODS FOR ENHANCING THE COATABILITY OF CARBON PASTES TOSUBSTRATES", which application is incorporated herein by reference inits entirety.

The so-prepared cathode paste is then placed onto the adhesion layer ofthe current collector described above by extrusion at a temperature offrom about 45° to about 48° C. A Mylar cover sheet is then placed overthe paste and the paste is spread to thickness of about 90 microns (μm)with a conventional plate and roller system and is cured by continuouslypassing the sheet through an electron beam apparatus (Electrocurtain,Energy Science Inc., Woburn, Mass.) at a voltage of about 175 kV and acurrent of about 1.0 mA and at a rate of about 1 cm/sec. After curing,the Mylar sheet is removed to provide for a solid cathode laminated tothe aluminum current collector described above. C. Electrolyte

56.51 grams of propylene carbonate, 14.13 grams of triglyme, and 17.56grams of urethane acrylate (Photomer 6140, available from Henkel Corp.,Coating and Chemical Division, Ambler, Pa.) are combined at roomtemperature until homogeneous. The resulting solution is passed througha column of 4 Å sodiated molecular sieves to remove water and then mixedat room temperature until homogeneous.

At this point, 2.57 grams of polyethylene oxide film forming agenthaving a number average molecular weight of about 600,000 (available asPolyox WSR-205 from Union Carbide Chemicals and Plastics, Danbury,Conn.) is added to the solution and then dispersed while stirring with amagnetic stirrer over a period of about 120 minutes. After dispersion,the solution is heated to between 60° C. and 65° C. with stirring untilthe film forming agent dissolved. The solution is cooled to atemperature of between 45° and 48° C., a thermocouple is placed at theedge of the vortex created by the magnetic stirrer to monitor solutiontemperature, and then 4.24 grams of LiPF₆ and 5.00 grams of Li(OCH₂CH₂)₃ OCH₃ are added to the solution over a 120 minute period whilethoroughly mixing to ensure a substantially uniform temperature profilethroughout the solution. Cooling is applied as necessary to maintain thetemperature of the solution between 45° and 48° C.

In one embodiment, the polyethylene oxide film forming agent is added tothe solution via a mini-sieve such as a 25 mesh mini-sieve commerciallyavailable as Order No. 57333-965 from VWR Scientific, San Francisco,Calif.

The resulting solution contains the following:

    ______________________________________                                        Component        Amount   Weight Percent.sup.2                                ______________________________________                                        Propylene carbonate                                                                            56.51 g  56.51                                               Triglyme         14.13 g  14.13                                               Urethane acrylate                                                                              17.56 g  17.56                                               LiPF.sub.6        4.24 g  4.24                                                Li(OCH.sub.2 CH.sub.2).sub.3 OCH.sub.3                                                          5.00 g  5.00                                                PEO film forming agent                                                                          2.57 g  2.57                                                Total              100 g  100                                                 ______________________________________                                         .sup.2  = weight percent based on the total weight of the electrolyte         solution (100 g)                                                         

This solution is then degassed to provide for an electrolyte solutionwherein little, if any, of the LiPF₆ salt decomposes.

Optionally, solutions produced as above and which contains theprepolymer, the polyalkylene oxide film forming agent, the electrolytesolvent and the LiPF₆ salt are filtered to remove any solid particles orgels remaining in the solution. One suitable filter device is a sinteredstainless steel screen having a pore size between 1 and 50 μm at 100%efficiency.

Alternatively, the electrolyte solution can be prepared in the followingmanner. Specifically, in this example, the mixing procedure is conductedusing the following weight percent of components:

    ______________________________________                                        Propylene carbonate                                                                            52.472 weight percent                                        Triglyme         13.099 weight percent                                        Urethane acrylate.sup.3                                                                        20.379 weight percent                                        LiPF.sub.6        5.720 weight percent                                        Li(OCH.sub.2 CH.sub.2).sub.3 OCH.sub.3                                                          5.000 weight percent                                        PEO film forming agent.sup.4                                                                    3.340 weight percent                                        ______________________________________                                         .sup.3 (Photomer 6140, available from Henkel Corp., Coating and Chemical      Division, Ambler, PA)                                                         .sup.4 Polyethylene oxide film forming agent having a number average          molecular weight of about 600,000 (available as Polyox WSR205 from Union      Carbide Chemicals and Plastics, Danbury, CT)                             

The mixing procedure employs the following steps:

1. Check the moisture level of the urethane acrylate. If the moisturelevel is less than 100 ppm water, proceed to step 2. If not, then firstdissolve the urethane acrylate at room temperature, <30° C. in thepropylene carbonate and triglyme and dry the solution over sodiated 4 Åmolecular sieves (Grade 514, 8-12 Mesh from Schoofs Inc., Moraga,Calif.).

2. Dry the propylene carbonate and triglyme over sodiated 4Å molecularsieves (Grade 514, 8-12 Mesh from Schoofs Inc., Moraga, Calif.).

3. At room temperature, <30° C., add the urethane acrylate to thesolvent prepared in step 2. Stir at 300 rpm until the resin iscompletely dissolved. The solution should be clear and colorless.

4. Dry and then sift the polyethylene oxide film forming agent through a25 mesh mini-sieve commercially available as Order No. 57333-965 fromVWR Scientific, San Francisco, Calif. While stirring at 300 rpm, add thedried and pre-sifted polyethylene oxide film forming agent slowing tothe solution. The polyethylene oxide film forming agent should be siftedinto the center of the vortex formed by the stirring means over a 30minute period. Addition of the polyethylene oxide film forming agentshould be dispersive and, during addition, the temperature should bemaintained at room temperature (<30° C.).

5. After final addition of the polyethylene oxide film forming agent,stir an additional 30 minutes to ensure that the film forming agent issubstantially dispersed.

6. Heat the mixture to 68° C. to 75° C. and stir until the film formingagent has melted and the solution has become transparent to light yellowin color. Optionally, in this step, the mixture is heated to 65° C. to68° C.

7. Cool the solution produced in step 6 and when the temperature of thesolution reaches 40° C. add the LiPF₆ salt and the lithium saltderivative very slowly making sure that the maximum temperature does notexceed 55° C.

8. After the final addition of the LiPF₆ salt, stir for an additional 30minutes, degas, and let sit overnight and cool.

9. Filter the solution through a sintered stainless steel screen havinga pore size between 1 and 50 μm at 100% efficiency.

At all times, the temperature of the solution should be monitored with athermocouple which should be placed in the vortex formed by the mixer.

Afterwards, the electrolyte mixture is then coated by a conventionalknife blade to a thickness of about 50 μm onto the surface of thecathode sheet prepared as above (on the side opposite that of thecurrent collector) but without the Mylar covering. The electrolyte isthen cured by continuously passing the sheet through an electron beamapparatus (Electrocurtain, Energy Science Inc., Woburn, Mass.) at avoltage of about 175 kV and a current of about 1.0 mA and at a conveyorspeed setting of 50 which provides for a conveyor speed of about 1cm/sec. After curing, a composite is recovered which contained a solidelectrolyte laminated to a solid cathode.

D. Anode

The anode comprises a sheet of lithium foil (about 76 μm thick) which iscommercially available from FMC Corporation Lithium Division, BessemerCity, N.C.

E. The Solid Electrolytic Cell

A sheet comprising a solid battery is prepared by laminating the lithiumfoil anode to the surface of the electrolyte in the sheet produced instep C above. Lamination is accomplished by minimal pressure.

What is claimed is:
 1. A solid, single-phase, solvent-containingelectrolyte which comprises:a solid polymeric matrix; and a solventcomprising about a 10:1 to 1:4 (w/w) mixture of an organic carbonate anda glyme, and an ionically conducting amount of an ion salt derivativeselected from the group consisting of: (a) an alkylene glycol(ether)derivative represented by Formula I:

    RO(R.sub.1 O).sub.p.sup.M                                  I

or represented by Formula II:

    MO(R.sub.1 O).sub.p M                                      II

where R is selected from the group consisting of alkyl of from 1 to 6carbon atoms, phenyl, alkphenyl of from 7 to 12 carbon atoms, and phenylsubstituted with 1 to 3 substituents selected from the group consistingof alkyl of from 1 to 4 carbon atoms, alkoxy of from 1 to 4 carbonatoms, chloro and bromo; R₁ is (CR₃ R₄)_(q) where R₃ and R₄ areindependently selected from the group consisting of hydrogen and alkylof from 1 to 4 carbon atoms, q is an integer from 1 to 6, and whereinwhen q is greater than 1, the R₃ and on each carbon atom may be the sameor different; M is a metal ion selected from the group consisting of Li,Na, K and Mg; and p is an integer of from 2 to 6; and (b) an ionsulfonate salt represented by Formula III:

    RO(R.sub.1 O).sub.p (CH.sub.2).sub.1 SO.sub.3 M            III

or represented by Formula IV:

    MSO.sub.3 (CH.sub.2).sub.s O(R.sub.1 O).sub.p (CH.sub.2).sub.r SO.sub.3 M IV

where M, R and R₁ are as defined above and r and s are independentlyintegers from 1 to 6; and (c) mixtures thereof.
 2. The solid,single-phase, solvent-containing electrolyte of claim 1, wherein theorganic carbonate is a cyclic aliphatic carbonate represented by theformula: ##STR4## where R₈, R₉, R₁₀, R₁₁, R₁₂, and R₁₃ are independentlyselected from the group consisting of hydrogen and alkyl of 1 or 2carbon atoms, and m is an integer equal to 0 or
 1. 3. The solid,single-phase, solvent-containing electrolyte of claim 1, wherein theorganic carbonate is a linear aliphatic carbonate represented by theformula:

    R.sub.14 [OC(O)].sub.n OR.sub.15 or R.sub.14 [OC(O)R.sub.16 ].sub.t OC(O)R.sub.15

where each R₁₄ and R₁₅ are independently selected from the groupconsisting of alkyl of from 1 to 4 carbon atoms; R₁₆ is an alkylenegroup of from 2 to 4 carbon atoms; n is an integer of from 1 to 2, and tis an integer from 1 to
 4. 4. The solid, single-phase,solvent-containing electrolyte of claim 1, wherein the glyme istriglyme, and wherein the weight ratio of organic carbonate to triglymeis about 4:1.
 5. The solid, single-phase, solvent-containing electrolyteof claim 1, wherein said ion salt derivative is an alkyleneglycol(ether) derivative represented by Formula I and wherein M islithium and p is
 3. 6. The solid, single-phase, solvent-containingelectrolyte of claim 1, wherein said ion salt derivative is an alkyleneglycol(ether) derivative represented by Formula II and wherein each M islithium and p is
 3. 7. The solid, single-phase, solvent-containingelectrolyte of claim 1, wherein said ion salt derivative is an ionsulfonate salt represented by Formula III and wherein M is lithium, p is3 and r and s are independently 3 or
 4. 8. The solid, single-phase,solvent-containing electrolyte of claim 1, wherein said ion saltderivative is an ion sulfonate salt represented by Formula IV andwherein each M is lithium, p is 3 and r and s are independently 3 or 4.9. The solid, single phase, solvent-containing electrolyte of claim 1,wherein said ion salt derivative is Li(OCH₂ CH₂)₃ OCH₃.
 10. The solid,single phase, solvent-containing electrolyte of claim 1, wherein saidion salt derivative is Li(OCH₂ CH₂)₃ OLi.
 11. The solid, single phase,solvent-containing electrolyte of claim 1, wherein said ion saltderivative is CH₃ (OCH₂ CH₂)₃ O(CH₂)₃ SO₃ Li.
 12. The solid, singlephase, solvent-containing electrolyte of claim 1, wherein said ion saltderivative is CH₃ (OCH₂ CH₂)₃ O(CH₂)₄ SO₃ Li.
 13. The solid, singlephase, solvent-containing electrolyte of claim 1, wherein said ion saltderivative is LiO₃ S(CH₂)₃ (OCH₂ CH₂)₃ O(CH₂)₃ SO₃ Li.
 14. The solid,single phase, solvent-containing electrolyte of claim 1, wherein saidion salt derivative is LiO₃ S(CH₂)₄ (OCH₂ CH₂)₃ O(CH₂)₄ SO₃ Li.
 15. Thesolid, single phase, solvent-containing electrolyte of claim 1, furtherincluding an inorganic ion salt.
 16. An electrolytic cell whichcomprises:an anode containing a compatible anodic material; cathodecontaining a compatible cathodic material; and interposed therebetween asolid, solvent-containing electrolyte which comprises: a solid polymericmatrix; and a solvent comprising about a 10:1 to 1:4 mixture of anorganic carbonate and a glyme, and an ion conducting amount of an ionsalt derivative selected from the group consisting of: (a) an alkyleneglycol(ether) derivative represented by Formula I:

    RO(R.sub.1 O).sub.p.sup.M                                  I

or represented by Formula II:

    MO(R.sub.1 O).sub.p M                                      II

where R is selected from the group consisting of alkyl of from 1 to 6carbon atoms, phenyl, alkphenyl of from 7 to 12 carbon atoms, and phenylsubstituted with 1 to 3 substituents selected from the group consistingof alkyl of from 1 to 4 carbon atoms, alkoxy of from 1 to 4 carbonatoms, chloro and bromo; R₁ is (CR₃ R₄)_(q) where R₃ and R₄ areindependently selected from the group consisting of hydrogen and alkylof from 1 to 4 carbon atoms, q being an integer from 1 to 6 and whereinwhen q is greater than 1, the R₃ and R₄ on each carbon atom may be thesame or different; M is a metal ion selected from the group consistingof Li, Na, K and Mg; and p is an integer of from 2 to 6; and (b) an ionsulfonate salt represented by Formula III:

    RO(R.sub.1 O).sub.p (CH.sub.2).sub.1 SO.sub.3 M            III

or represented by Formula IV:

    MSO.sub.3 (CH.sub.2).sub.s O(R.sub.1 O).sub.p (CH.sub.2).sub.r SO.sub.3 M IV

where M, R and R₁ are as defined above and r and s are independentlyintegers from 1 to 6; and (c) mixtures thereof.
 17. The electrolyticcell of claim 16, wherein the organic carbonate is a cyclic aliphaticcarbonate represented by the formula: ##STR5## where R₈, R₉, R₁₀, R₁₁,R₁₂, and R₁₃ are independently selected from the group consisting ofhydrogen and alkyl of from 1 to 2 carbon atoms, and m is an integerequal to 0 or
 1. 18. The electrolytic cell of claim 16, wherein theorganic carbonate is a linear aliphatic carbonate represented by theformula:

    R.sub.14 [OC(O)].sub.n OR.sub.15 and R.sub.14 [OC(O)R.sub.16 ].sub.t OC(O)R.sub.15

where each R₁₄ and R₁₅ are independently selected from the groupconsisting of alkyl of from 1 to 4 carbon atoms; R₁₆ is an alkylenegroup of from 2 to 4 carbon atoms; n is an integer of from 1 to 2, and tis an integer from 1 to
 4. 19. The electrolytic cell of claim 16,wherein the glyme is triglyme, and wherein the molar ratio of organiccarbonate to triglyme is about 4:1.
 20. The electrolytic cell of claim16, wherein said ion salt derivative is an alkylene glycol(ether)derivative represented by Formula I and wherein M is lithium and p is 3.21. The electrolytic cell of claim 16, wherein said ion salt derivativeis an alkylene glycol(ether) derivative represented by Formula II andwherein each M is lithium and p is
 3. 22. The electrolytic cell of claim16, wherein said lithium salt derivative is a lithium sulfonate saltrepresented by Formula III and wherein M is lithium, p is 3 and r and sare independently 3 or
 4. 23. The electrolytic cell of claim 16, whereinsaid ion salt derivative is an ion sulfonate salt represented by FormulaIV and wherein M is lithium, p is 3 and r and s are independently 3 or4.
 24. The electrolytic cell of claim 16, wherein said ion saltderivative is Li(OCH₂ CH₂)₃ OCH₃.
 25. The electrolytic cell of claim 16,wherein said ion salt derivative is Li(OCH₂ CH₂)₃ OLi.
 26. Theelectrolytic cell of claim 16, wherein said ion salt derivative is CH₃(OCH₂ CH₂)₃ O(CH₂)₃ SO₃ Li.
 27. The electrolytic cell of claim 16,wherein said ion salt derivative is CH₃ (OCH₂ CH₂)₃ O(CH₂)₄ SO₃ Li. 28.The electrolytic cell of claim 16, wherein said ion salt derivative isLiO₃ S(CH₂)₃ (OCH₂ CH₂)₃ O(CH₂)₃ SO₃ Li.
 29. The electrolytic cell ofclaim 16, wherein said ion salt derivative is LiO₃ S(CH₂)₄ (OCH₂ CH₂)₃O(CH₂)₄ SO₃ Li.
 30. A method for enhancing the cumulative capacity of anelectrolytic cell which comprises an anode containing a compatibleanodic material, a cathode containing a compatible cathodic material,and interposed therebetween a solid, solvent-containing electrolytecontaining a solid polymeric matrix and a solvent comprising about a10:1 to 1:4 (w/w) mixture of an organic carbonate and a glyme, whichmethod comprises including in said electrolyte an ion salt derivativecomprising:(a) an alkylene glycol(ether) derivative represented byFormula I:

    RO(R.sub.1 O).sub.p M                                      I

or represented by Formula II:

    MO(R.sub.1 O).sub.p M                                      II

where R is selected from the group consisting of alkyl of from 1 to 6carbon atoms, phenyl, alkphenyl of from 7 to 12 carbon atoms, and phenylsubstituted with 1 to 3 substituents selected from the group consistingof alkyl of from 1 to 4 carbon atoms, alkoxy of from 1 to 4 carbonatoms, chloro and bromo; R₁ is (CR₃ R₄)_(q) where R₃ and R₄ areindependently selected from the group consisting of hydrogen and alkylof from 1 to 4 carbon atoms, q being an integer from 1 to 6 and whereinwhen q is greater than 1, the R₃ and R₄ on each carbon atom may be thesame or different; M is a metal ion selected from the group consistingof Li, Na, K and Mg; and p is an integer of from 2 to 6; or (b) an ionsulfonate salt represented by Formula III:

    RO(R.sub.1 O).sub.p (CH.sub.2).sub.r SO.sub.3 M            III

or represented by Formula IV:

    MSO.sub.3 (CH.sub.2).sub.s O(R.sub.1 O).sub.p (CH.sub.2).sub.r SO.sub.3 M IV

where M, R₁ and R₂ are as defined above and r and s are independentlyintegers from 1 to 6; or (c) mixtures thereof.
 31. The method of claim30, wherein said ion salt derivative is Li(OCH₂ CH₂)₃ OCH₃.
 32. Themethod of claim 30, wherein said ion salt derivative is Li(OCH₂ CH₂)₃OLi.
 33. The method of claim 30, wherein said ion salt derivative is CH₃(OCH₂ CH₂)₃ O(CH₂)₃ SO₃ Li.
 34. The method of claim 30, wherein said ionsalt derivative is CH₃ (OCH₂ CH₂)₃ O(CH₂)₄ SO₃ Li.
 35. The method ofclaim 30, wherein said ion salt derivative is LiO₃ S(CH₂)₃ (OCH₂ CH₂)₃O(CH₂)₃ SO₃ Li.
 36. The method of claim 30, wherein said ion saltderivative is LiO₃ S(CH₂)₄ (OCH₂ CH₂)₃ O(CH₂)₄ SO₃ Li.
 37. Theelectrolytic cell of claim 16, wherein the anode is an intercalationbased anode comprising carbon.